A wireless sensor network is being applied to various fields such as an environment control of intelligent buildings and factories, an automatic control of a production process, distribution management, articles and information management in hospitals, a remote check of patients' condition, etc. Recently, the wireless sensor network is core infra technology of a ubiquitous wireless network, and becomes increasingly more important.
A sensor network is a wired/wireless network configured with sensors that are ultralight and consume low power compared to a general computer network. The sensor network performs important roles such as collecting data and controlling equipment. Therefore, security is very important in a sensor network.
Examples of important issues of the wireless sensor network include authentication and security, in addition to miniaturizing of equipment, enhancing of a sensing ability, stable and fast routing, and power control. However, in the wireless sensor network, when sensor nodes accessing a base station desire to transmit/receive data, due to a feature of wireless transmission/reception, a malicious hacker may hack the transmitted/received data in the middle.
For security functions such as authentication and encryption, key exchange and management is preferentially required, various key management techniques for the sensor network are researched. To solve the security problems of the sensor network, technologies for key exchange, authentication, and encryption necessary for security in the sensor network are disclosed in Korean Patent Publication No. 10-2011-0113379 and Korean Patent Publication No. 10-2005-0068949.
Examples of a related art sensor network key managing method include a method that exchanges a key by using a plaintext at an initial step, a management method based on a network key and a group key in which a key to be used in a network or a group is previously set and used, and a method of using a reliable base station.
However, in the above-described related art methods, since a key to be used is exposed and transferred as a plaintext, a security attacker can easily hack the key. The above-described related art methods have a difficulty in that a secret key should be previously input to a sensor node. Furthermore, there is a problem in that an input device is limited for a lightened sensor network, but a master key of a base station should be input to a sensor node.
Among the related art key managing methods, as a method of performing a security connection without directly inputting a key to a node, there is Wi-Fi Protected Setup (WPS) technology. The WPS technology is a method in which when a user pushes a button, a key is transferred through message exchange. However, an attacker can intrude at a time when a user pushes a button.
The related art sensor network security key managing methods have the above-described problems, and moreover, security is weakened with time after installation. In detail, since a complicated encryption method cannot be used due to a characteristic of the sensor network, a low-level encryption method is used, and for this reason, a probability that a code is broken increases with time, causing security to be weakened with time.